Many enduro bikes have don't have a crossbar. Many streetfighters with high handlebars don't have one, although it is ideal for mounting some interesting accessories:

Roadbook holders

GPS mounts

Motorcycle computers

Map holders

and many more

These universal crossbars fit handlebars with 22 to 25mm diameter (standard steel or aluminium handlebars and MAGURA or ProTaper handlebars that have a conical shape). Easily removeable if you don't need a crossbar all the time. Anodized solid aluminum.

The 320mm is the most popular crossbar for most Magura and ProTaper Dirtbike handlebars. 320 mm (or approx. 12.5 inches) is the total length of the aluminum bar only (not hole-to hole, and not counting the clamps, like the length of a stick). Diameter is approx. 12mm or 1/2".